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1
Yamamoto, A., R. Murao, Y. Suzuki e Y. Aoi. "A Quasi-Unsteady Study on Wake Interaction of Turbine Stator and Rotor Cascades". Journal of Turbomachinery 117, n. 4 (1 ottobre 1995): 553–61. http://dx.doi.org/10.1115/1.2836567.
Testo completoAbstract (sommario):
Detailed flow measurements were made to study cascade interaction of turbine stator and rotor, using two linear cascades installed in series. The upstream cascade was moved to several places in the cascade pitchwise direction in order to change the relative location between the two cascades, and measurements were made in the downstream cascade. The result shows that the net total pressure loss generated in the downstream cascade becomes maximum when wakes of the upstream cascade pass the suction side of the downstream cascade passage, while the tip leakage loss generated in the downstream cascade does not change with the relative location of the cascades. The upstream cascade wakes interact with the secondary flows and most strongly with the endwall flow in the downstream cascade passage, making the loss distributions in the cascades fairly unsteady.
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Lee, Yoo Seok, Koun Lim e Shelley D. Minteer. "Cascaded Biocatalysis and Bioelectrocatalysis: Overview and Recent Advances". Annual Review of Physical Chemistry 72, n. 1 (20 aprile 2021): 467–88. http://dx.doi.org/10.1146/annurev-physchem-090519-050109.
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Enzyme cascades are plentiful in nature, but they also have potential in artificial applications due to the possibility of using the target substrate in biofuel cells, electrosynthesis, and biosensors. Cascade reactions from enzymes or hybrid bioorganic catalyst systems exhibit extended substrate range, reaction depth, and increased overall performance. This review addresses the strategies of cascade biocatalysis and bioelectrocatalysis for ( a) CO2 fixation, ( b) high value-added product formation, ( c) sustainable energy sources via deep oxidation, and ( d) cascaded electrochemical enzymatic biosensors. These recent updates in the field provide fundamental concepts, designs of artificial electrocatalytic oxidation-reduction pathways (using a flexible setup involving organic catalysts and engineered enzymes), and advances in hybrid cascaded sensors for sensitive analyte detection.
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Littmann, Enno, e Helge Ritter. "Learning and Generalization in Cascade Network Architectures". Neural Computation 8, n. 7 (ottobre 1996): 1521–39. http://dx.doi.org/10.1162/neco.1996.8.7.1521.
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Incrementally constructed cascade architectures are a promising alternative to networks of predefined size. This paper compares the direct cascade architecture (DCA) proposed in Littmann and Ritter (1992) to the cascade-correlation approach of Fahlman and Lebiere (1990) and to related approaches and discusses the properties on the basis of various benchmark results. One important virtue of DCA is that it allows the cascading of entire subnetworks, even if these admit no error-backpropagation. Exploiting this flexibility and using LLM networks as cascaded elements, we show that the performance of the resulting network cascades can be greatly enhanced compared to the performance of a single network. Our results for the Mackey-Glass time series prediction task indicate that such deeply cascaded network architectures achieve good generalization even on small data sets, when shallow, broad architectures of comparable size suffer from overfitting. We conclude that the DCA approach offers a powerful and flexible alternative to existing schemes such as, e.g., the mixtures of experts approach, for the construction of modular systems from a wide range of subnetwork types.
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Suzuki, Daiki, Sho Tsugawa, Keiichiro Tsukamoto e Shintaro Igari. "On the effectiveness of a contrastive cascade graph learning framework: The power of synthetic cascade data". PLOS ONE 18, n. 10 (16 ottobre 2023): e0293032. http://dx.doi.org/10.1371/journal.pone.0293032.
Testo completoAbstract (sommario):
Analyzing the dynamics of information diffusion cascades and accurately predicting their behavior holds significant importance in various applications. In this paper, we concentrate specifically on a recently introduced contrastive cascade graph learning framework, for the task of predicting cascade popularity. This framework follows a pre-training and fine-tuning paradigm to address cascade prediction tasks. In a previous study, the transferability of pre-trained models within the contrastive cascade graph learning framework was examined solely between two social media datasets. However, in our present study, we comprehensively evaluate the transferability of pre-trained models across 13 real datasets and six synthetic datasets. We construct several pre-trained models using real cascades and synthetic cascades generated by the independent cascade model and the Profile model. Then, we fine-tune these pre-trained models on real cascade datasets and evaluate their prediction accuracy based on the mean squared logarithmic error. The main findings derived from our results are as follows. (1) The pre-trained models exhibit transferability across diverse types of real datasets in different domains, encompassing different languages, social media platforms, and diffusion time scales. (2) Synthetic cascade data prove effective for pre-training purposes. The pre-trained models constructed with synthetic cascade data demonstrate comparable effectiveness to those constructed using real data. (3) Synthetic cascade data prove beneficial for fine-tuning the contrastive cascade graph learning models and training other state-of-the-art popularity prediction models. Models trained using a combination of real and synthetic cascades yield significantly lower mean squared logarithmic error compared to those trained solely on real cascades. Our findings affirm the effectiveness of synthetic cascade data in enhancing the accuracy of cascade popularity prediction.
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Zhang, Shuyi, Bo Yang, Hong Xie e Moru Song. "Applications of an Improved Aerodynamic Optimization Method on a Low Reynolds Number Cascade". Processes 8, n. 9 (14 settembre 2020): 1150. http://dx.doi.org/10.3390/pr8091150.
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The effect of cascade aerodynamic optimization on turbomachinery design is very significant. However, for most traditional cascade optimization methods, aerodynamic parameters are considered as boundary conditions and rarely directly used as the optimization variables to realize optimization. Given this problem, this paper proposes an improved cascade aerodynamic optimization method in which an incidence angle and nine geometric parameters are used to parameterize the cascade and one modified optimization algorithm is adopted to find the cascade with the optimal aerodynamic performance. The improved parameterization approach is based on the Non-Uniform Rational B-Splines (NURBS) method, the camber line superposing thickness distribution molding (CLSTDM) method, and the plane cascade design method. To rapidly and effectively find the cascade with the largest average lift-drag ratio within a certain range of incidence angles, modified particle swarm optimization combined with the modified very fast simulated annealing algorithm (PSO-MVFSA) is adopted. To verify the feasibility of the method, a cascade with NACA4412 and a practical cascade are optimized. It is found that the average lift-drag ratios of two optimal performance cascades are respectively increased by 13.38% and 15.21% in comparison to those of two original cascades. Meanwhile, through optimizing the practical cascade of the Blade D500, under different volume flow rates, the pressure coefficient of the optimized cascade is increased by an average of more than 6.12% compared to that of the prototype, and the average efficiency is increased by 11.15%. Therefore, this improved aerodynamic optimization method is reliable and feasible for the performance improvement of cascades with a low Reynolds number.
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Azizov, T. E., A. Yu Smirnov e G. A. Sulaberidze. "Comparison of the efficiency of square cascades with an additional product flow and double cascades to concentrate intermediate isotopes". Journal of Physics: Conference Series 2147, n. 1 (1 gennaio 2022): 012006. http://dx.doi.org/10.1088/1742-6596/2147/1/012006.
Testo completoAbstract (sommario):
Abstract Original techniques were proposed for calculating and optimizing double cascades (DC) built of square cascades and a square cascade with an additional product flow (SCAP). Both cascade schemes (DC and SCAP) were tested in solving a task of simultaneous enrichment of three components of a model mixture to a pre-defined level. A comparison of the DC and SCAP efficiency was made according to the minimum of total cascade flow. The results have shown that the double cascade is more efficient in terms of the chosen criterion.
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Lipp, Vladimir, Igor Milov e Nikita Medvedev. "Quantifying electron cascade size in various irradiated materials for free-electron laser applications". Journal of Synchrotron Radiation 29, n. 2 (15 febbraio 2022): 323–30. http://dx.doi.org/10.1107/s1600577522000339.
Testo completoAbstract (sommario):
Studying electron- and X-ray-induced electron cascades in solids is essential for various research areas at free-electron laser facilities, such as X-ray imaging, crystallography, pulse diagnostics or X-ray-induced damage. To better understand the fundamental factors that define the duration and spatial size of such cascades, this work investigates the electron propagation in ten solids relevant for the applications of X-ray lasers: Au, B4C, diamond, Ni, polystyrene, Ru, Si, SiC, Si3N4 and W. Using classical Monte Carlo simulation in the atomic approximation, we study the dependence of the cascade size on the incident electron or photon energy and on the target parameters. The results show that an electron-induced cascade is systematically larger than a photon-induced cascade. Moreover, in contrast with the common assumption, the maximal cascade size does not necessarily coincide with the electron range. It was found that the cascade size can be controlled by careful selection of the photon energy for a particular material. Photon energy, just above an ionization potential, can essentially split the absorbed energy between two electrons (photo- and Auger), reducing their initial energy and thus shrinking the cascade size. This analysis suggests a way of tailoring the electron cascades for applications requiring either small cascades with a high density of excited electrons or large-spread cascades with lower electron densities.
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Yocum, A. M., e W. F. O’Brien. "Separated Flow in a Low-Speed Two-Dimensional Cascade: Part II—Cascade Performance". Journal of Turbomachinery 115, n. 3 (1 luglio 1993): 421–34. http://dx.doi.org/10.1115/1.2929269.
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This study was conducted for the purpose of providing a more fundamental understanding of separated flow in cascades and to provide performance data for fully stalled blade rows. Cascades of a single blade geometry and a solidity of unity were studied for three stagger angles and the full range of angle of attack extending well into the stalled flow regime. The Reynolds number was also varied for a limited number of cases. Results from velocity and pressure measurements made in the cascade and the overall cascade performance evaluated from these measurements are presented. In addition, results from a numerical simulation of the flow through a cascade of flat plate airfoils are used to illustrate further the effects of blade stagger and to define the correct limits for the cascade performance. The results indicate that the slope of the total pressure loss versus angle of attack curve for the flow immediately downstream of the cascade is steeper for cascades with greater stagger. The normal force coefficient was found to increase to a peak value near the angle of attack where full leading edge stall first occurs. A further increase in angle of attack results in a decline in the normal force coefficient. The peak value of the normal force coefficient is greater and occurs at a higher angle of attack for the cascades with smaller stagger.
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Amour, A., M. Bird, L. Chaudry, J. Deadman, D. Hayes e C. Kay. "General considerations for proteolytic cascades". Biochemical Society Transactions 32, n. 1 (1 febbraio 2004): 15–16. http://dx.doi.org/10.1042/bst0320015.
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Proteases are involved in the regulation of a wide variety of essential physiological processes, often by participating in a highly orchestrated sequence of events termed a ‘proteolytic cascade’. Four major proteolytic cascades with disease relevance are candidates for therapeutic intervention, namely caspase-mediated apoptosis, blood coagulation, the matrix metalloproteinase cascade and the complement cascade. Understanding the various steps involved in the functioning of a cascade is key to deciding possible points of intervention for the design of potential drug molecules. This brief review illustrates some of the common features of proteolytic cascades using the blood coagulation pathway as an example.
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Milner, Jo. "Molecular cascades in the Cascade Mountains". Trends in Genetics 12, n. 9 (settembre 1996): 372–73. http://dx.doi.org/10.1016/s0168-9525(96)80023-0.
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Abufouda, Mohammed. "Postmortem Analysis of Decayed Online Social Communities: Cascade Pattern Analysis and Prediction". Complexity 2018 (9 ottobre 2018): 1–17. http://dx.doi.org/10.1155/2018/3873601.
Testo completoAbstract (sommario):
Recently, many online social networks, such as MySpace, Orkut, and Friendster, have faced inactivity decay of their members, which contributed to the collapse of these networks. The reasons, mechanics, and prevention mechanisms of such inactivity decay are not fully understood. In this work, we analyze decayed and alive subwebsites from the Stack Exchange platform. The analysis mainly focuses on the inactivity cascades that occur among the members of these communities. We provide measures to understand the decay process and statistical analysis to extract the patterns that accompany the inactivity decay. Additionally, we predict cascade size and cascade virality using machine learning. The results of this work include a statistically significant difference of the decay patterns between the decayed and the alive subwebsites. These patterns are mainly cascade size, cascade virality, cascade duration, and cascade similarity. Additionally, the contributed prediction framework showed satisfactorily prediction results compared to a baseline predictor. Supported by empirical evidence, the main findings of this work are (1) there are significantly different decay patterns in the alive and the decayed subwebsites of the Stack Exchange; (2) the cascade’s node degrees contribute more to the decay process than the cascade’s virality, which indicates that the expert members of the Stack Exchange subwebsites were mainly responsible for the activity or inactivity of the Stack Exchange subwebsites; (3) the Statistics subwebsite is going through decay dynamics that may lead to it becoming fully-decayed; (4) the decay process is not governed by only one network measure, it is better described using multiple measures; (5) decayed subwebsites were originally less resilient to inactivity decay, unlike the alive subwebsites; and (6) network’s structure in the early stages of its evolution dictates the activity/inactivity characteristics of the network.
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Dzhatdoev, Timur, Emil Khalikov, Anna Kircheva, Egor Podlesnyi e Anastasia Telegina. "Intergalactic electromagnetic cascades in the magnetized Universe as a tool of astroparticle physics". EPJ Web of Conferences 191 (2018): 08009. http://dx.doi.org/10.1051/epjconf/201819108009.
Testo completoAbstract (sommario):
We review the physics of intergalactic electromagnetic cascades in the presence of the extragalactic magnetic field (EGMF). Various regimes of intergalactic electromagnetic cascades are considered depending on the number of cascade generations, the value of the cascade electron deflection angle, and the relations between the EGMF coherence length, typical cascade γ-ray mean free path, and electron energy loss length. We also review contemporary constraints on the EGMF parameters and explore the sensitivity of various γ-ray instruments to the EGMF parameters.
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VENEZIANO, DANIELE, e ANDREAS LANGOUSIS. "THE MAXIMUM OF MULTIFRACTAL CASCADES: EXACT DISTRIBUTION AND APPROXIMATIONS". Fractals 13, n. 04 (dicembre 2005): 311–24. http://dx.doi.org/10.1142/s0218348x0500291x.
Testo completoAbstract (sommario):
We study the distribution of the maximum M of multifractal measures using discrete cascade representations. For such discrete cascades, the exact distribution of M can be found numerically. We evaluate the sensitivity of the distribution of M to simplifying approximations, including independence of the measure among the cascade tiles and replacement of the dressing factor by a random variable with the same distribution type as the cascade generator. We also examine how the distribution of M varies with the dimensionality of the support and the multiplicity of the cascade. Of these factors, dependence of the measure among different cascade tiles has the highest effect on the distribution of M. This effect comes mainly from long-range dependence. We use these findings to propose a simple approximation to the distribution of M and give charts to implement the approximation for beta-lognormal cascades.
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Klose, Ann Kristin, Nico Wunderling, Ricarda Winkelmann e Jonathan F. Donges. "What do we mean, ‘tipping cascade’?" Environmental Research Letters 16, n. 12 (1 dicembre 2021): 125011. http://dx.doi.org/10.1088/1748-9326/ac3955.
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Abstract Based on suggested interactions of potential tipping elements in the Earth’s climate and in ecological systems, tipping cascades as possible dynamics are increasingly discussed and studied. The activation of such tipping cascades would impose a considerable risk for human societies and biosphere integrity. However, there are ambiguities in the description of tipping cascades within the literature so far. Here we illustrate how different patterns of multiple tipping dynamics emerge from a very simple coupling of two previously studied idealized tipping elements. In particular, we distinguish between a two phase cascade, a domino cascade and a joint cascade. A mitigation of an unfolding two phase cascade may be possible and common early warning indicators are sensitive to upcoming critical transitions to a certain degree. In contrast, a domino cascade may hardly be stopped once initiated and critical slowing down-based indicators fail to indicate tipping of the following element. These different potentials for intervention and anticipation across the distinct patterns of multiple tipping dynamics should be seen as a call to be more precise in future analyses of cascading dynamics arising from tipping element interactions in the Earth system.
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Li, Gang, Tao Meng, Min Li, Mingle Zhou e Delong Han. "A Dynamic Short Cascade Diffusion Prediction Network Based on Meta-Learning-Transformer". Electronics 12, n. 4 (7 febbraio 2023): 837. http://dx.doi.org/10.3390/electronics12040837.
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The rise of social networks has greatly contributed to creating information cascades. Over time, new nodes are added to the cascade network, which means the cascade network is dynamically variable. At the same time, there are often only a few nodes in the cascade network before new nodes join. Therefore, it becomes a key task to predict the diffusion after the dynamic cascade based on the small number of nodes observed in the previous period. However, existing methods are limited for dynamic short cascades and cannot combine temporal information with structural information well, so a new model, MetaCaFormer, based on meta-learning and the Transformer structure, is proposed in this paper for dynamic short cascade prediction. Considering the limited processing capability of traditional graph neural networks for temporal information, we propose a CaFormer model based on the Transformer structure, which inherits the powerful processing capability of Transformer for temporal information, while considering the neighboring nodes, edges and spatial importance of nodes, effectively combining temporal and structural information. At the same time, to improve the prediction ability for short cascades, we also fuse meta-learning so that it can be quickly adapted to short cascade data. In this paper, MetaCaFormer is applied to two publicly available datasets in different scenarios for experiments to demonstrate its effectiveness and generalization ability. The experimental results show that MetaCaFormer outperforms the currently available baseline methods.
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Lapuzin, Alexander, Valery Subotovich, Yuriy Yudin, Svetlana Naumenko e Ivan Malymon. "Studying the Effect of the Tangential Nonuniformity of Flow Parameters on Gas Dynamic Performances of the Nozzle Cascades of Turbine Machines". NTU "KhPI" Bulletin: Power and heat engineering processes and equipment, n. 1-2 (28 dicembre 2022): 23–31. http://dx.doi.org/10.20998/2078-774x.2022.01.03.
Testo completoAbstract (sommario):
Aerodynamic efficiency of the nozzle cascades of steam and gas turbines is defined by many factors and one of them is the tangential and radial nonuniformity degree of the parameters of a spatial flow behind the cascades. The averaging of these parameters enables the determination of the integral parameters of the cascades, in particular two flow angles and the velocity angle or the kinetic energy loss coefficient. The angle that takes into account the level of the averaged radial component of the velocity defines the level of kinematic losses in the cascade. Even in the case of the cylindric boundaries of the cascade this angle differs from zero and kinematic losses decrease the cascade efficiency by 30 to 50 percent. This scientific paper gives the results of experimental investigations of the effect of the circumferential nonuniformity of the velocity and the angles of the spatial flow on kinematic losses at different radii of the nozzle cascade of the last stage of the steam turbine and the nozzle cascade of the first stage of the gas turbine. The kinetic energy loss coefficient and the coefficient of total losses were suggested as the integral characteristics of the cascades. In the case of cylindric boundaries of the stage the total loss-to-kinetic energy loss ratio is noticeably decreased during the transition from the average zone to the zone of end losses. However, in the peripheral zone of the nozzle cascade of the last stage of steam turbine total losses are three times higher than kinetic energy losses due to the fact that the radial component of the velocity behind the cascade is much higher than the flow rate component and the level of the losses of kinetic energy is not high.
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WISE, FRANK, LIEJIA QIAN e XIANG LIU. "APPLICATIONS OF CASCADED QUADRATIC NONLINEARITIES TO FEMTOSECOND PULSE GENERATION". Journal of Nonlinear Optical Physics & Materials 11, n. 03 (settembre 2002): 317–38. http://dx.doi.org/10.1142/s0218863502001024.
Testo completoAbstract (sommario):
Useful nonlinear phase shifts can be produced in cascaded quadratic processes. The issues that arise in the extension of cascade nonlinearities to the femtosecond regime are outlined in this paper, and initial applications of the cascade phase shifts to femtosecond pulse generation and propagation are reviewed. The results demonstrate that the cascade phase shifts offer unique properties, and in some cases pulse-shaping techniques based on cascade nonlinearities have potential to offer substantial performance improvements over existing approaches.
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Kedziora, David J., Romesh Abeysuriya, Cliff C. Kerr, George L. Chadderdon, Vlad-Ștefan Harbuz, Sarah Metzger, David P. Wilson e Robyn M. Stuart. "The Cascade Analysis Tool: software to analyze and optimize care cascades". Gates Open Research 3 (7 giugno 2019): 1488. http://dx.doi.org/10.12688/gatesopenres.13031.1.
Testo completoAbstract (sommario):
Introduction: Cascades, which track the progressive stages of engagement on the path towards a successful outcome, are increasingly being employed to quantitatively assess progress towards targets associated with health and development responses. Maximizing the proportion of people with successful outcomes within a budget-constrained context requires identifying and implementing interventions that are not only effective, but also cost-effective. Methods: We developed a software application called the Cascade Analysis Tool that implements advanced analysis and optimization methods for understanding cascades, combined with the flexibility to enable application across a wide range of areas in health and development. The tool allows users to design the cascade, collate and enter data, and then use the built-in analysis methods in order to answer key policy questions, such as: understanding where the biggest drop-offs along the cascade are; visualizing how the cascade varies by population; investigating the impact of introducing a new intervention or scaling up/down existing interventions; and estimating how available funding should be optimally allocated among available interventions in order to achieve a variety of different objectives selectable by the user (such as optimizing cascade outcomes in target years). The Cascade Analysis Tool is available via a user-friendly web-based application, and comes with a user guide, a library of pre-made examples, and training materials. Discussion: Whilst the Cascade Analysis Tool is still in the early stages of existence, it has already shown promise in preliminary applications, and we believe there is potential for it to help make sense of the increasing quantities of data on cascades.
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Kedziora, David J., Romesh Abeysuriya, Cliff C. Kerr, George L. Chadderdon, Vlad-Ștefan Harbuz, Sarah Metzger, David P. Wilson e Robyn M. Stuart. "The Cascade Analysis Tool: software to analyze and optimize care cascades". Gates Open Research 3 (24 dicembre 2019): 1488. http://dx.doi.org/10.12688/gatesopenres.13031.2.
Testo completoAbstract (sommario):
Introduction: Cascades, which track the progressive stages of engagement on the path towards a successful outcome, are increasingly being employed to quantitatively assess progress towards targets associated with health and development responses. Maximizing the proportion of people with successful outcomes within a budget-constrained context requires identifying and implementing interventions that are not only effective, but also cost-effective. Methods: We developed a software application called the Cascade Analysis Tool that implements advanced analysis and optimization methods for understanding cascades, combined with the flexibility to enable application across a wide range of areas in health and development. The tool allows users to design the cascade, collate and enter data, and then use the built-in analysis methods in order to answer key policy questions, such as: understanding where the biggest drop-offs along the cascade are; visualizing how the cascade varies by population; investigating the impact of introducing a new intervention or scaling up/down existing interventions; and estimating how available funding should be optimally allocated among available interventions in order to achieve a variety of different objectives selectable by the user (such as optimizing cascade outcomes in target years). The Cascade Analysis Tool is available via a user-friendly web-based application, and comes with a user guide, a library of pre-made examples, and training materials. Discussion: Whilst the Cascade Analysis Tool is still in the early stages of existence, it has already shown promise in preliminary applications, and we believe there is potential for it to help make sense of the increasing quantities of data on cascades.
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Zhao, Chang Yu, Meng Xiao Bo, Jian Yong Zhu e Guang Li Li. "Numerical Study of Wakes on Downstream Effects in Static Cascade Flow Field to Simulation of Rotor Wake". Advanced Materials Research 805-806 (settembre 2013): 1865–69. http://dx.doi.org/10.4028/www.scientific.net/amr.805-806.1865.
Testo completoAbstract (sommario):
The effects of moving wakes on the compressor cascade flow are discussed in this article, which can be regarded as the flow simulation between stages of compressor cascade. The moving wakes are simulated by moving cylinder before a compressor cascade flow. Different flow situations by changing the angle of wakes direction are presented by numerical simulation. The performance of cascade influenced by cylinder wakes can be related to several parameters, such as the distance between cascades in the shaft direction, the angle of wake direction. Loss of the cascade changes along with those parameters whose optimal direction is demonstrated.
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Fritzsche, Stephan, Patrick Palmeri e Stefan Schippers. "Atomic Cascade Computations". Symmetry 13, n. 3 (23 marzo 2021): 520. http://dx.doi.org/10.3390/sym13030520.
Testo completoAbstract (sommario):
Atomic cascades are ubiquitous in nature and they have been explored within very different scenarios, from precision measurements to the modeling of astrophysical spectra, and up to the radiation damage in biological matter. However, up to the present, a quantitative analysis of these cascades often failed because of their inherent complexity. Apart from utilizing the rotational symmetry of atoms and a proper distinction of different physical schemes, a hierarchy of useful approaches is therefore needed in order to keep cascade computations feasible. We here suggest a classification of atomic cascades and demonstrate how they can be modeled within the framework of the Jena Atomic Calculator. As an example, we shall compute within a configuration-average approach the stepwise decay cascade of atomic magnesium, following a 1s inner-shell ionization, and simulate the corresponding (final) ion distribution. Our classification of physical scenarios (schemes) and the hierarchy of computational approaches are both flexible to further refinements as well as to complex shell structures of the atoms and ions, for which the excitation and decay dynamics need to be modeled in good detail.
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Sekretarev, Yuri, Sherkhon Sultonov e Victor Shalnev. "Optimal Control Mode of the Vakhsh Hydropower Reservoirs to Reduce Electricity Shortages in Tajikistan". Applied Mechanics and Materials 792 (settembre 2015): 446–50. http://dx.doi.org/10.4028/www.scientific.net/amm.792.446.
Testo completoAbstract (sommario):
The paper is aimed to determine runoff limits of the Vakhsh cascade hydropower plant, which are the main parameters when setting optimum modes of the hydropower plant. It is proposed to increase power generation of the hydropower plant of the Vakhsh cascade by assigning the optimal modes of operation of hydropower plants. The peculiarities of managing the cascades of hydropower plants are described. The description of the Vakhsh cascade hydropower plant and the method of controlling the reservoir of the cascade of the hydropower plants are given.
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Huang, Xue, Jingyuan L. Zhang, Vadim Tokranov, Serge Oktyabrsky e Claire F. Gmachl. "Same-wavelength cascaded-transition quantum cascade laser". Applied Physics Letters 103, n. 5 (29 luglio 2013): 051113. http://dx.doi.org/10.1063/1.4817737.
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Anandaram, Harishchander. "Modeling of Cascade Regulation in Psoriasis: A Comprehensive Approach". ECS Transactions 107, n. 1 (24 aprile 2022): 2627–35. http://dx.doi.org/10.1149/10701.2627ecst.
Testo completoAbstract (sommario):
The implication of a successful mathematical model in applied genomics requires mathematical modeling of regulatory cascades in a gene-regulated network in autoimmune disorders (AIDs) such as psoriasis, is a difficult job to complete in the current age of applied genomics. There were four computational approaches used to address the challenge: (a) Gene Assisted Cascade Regulation, (b) Differential Gene Expression Cascade, (c) Gene Variant Cascade, and (d) Biologic Cascade to identify a potential biomarker for treating AIDS in the future, and finally, the reconstructed network concerning activation and deactivation loops that were subjected to mathematical modeling to understand and identify the mechanism of regulatory cascade in pathogenesis.
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Li, Jiqing, e Xiong Yang. "Mid and long-term optimize scheduling of cascade hydro-power stations based on modified GA-POA method". Proceedings of the International Association of Hydrological Sciences 379 (5 giugno 2018): 199–203. http://dx.doi.org/10.5194/piahs-379-199-2018.
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Abstract. In this paper, to explore the efficiency and rationality of the cascade combined generation, a cascade combined optimal model with the maximum generating capacity is established, and solving the model by the modified GA-POA method. It provides a useful reference for the joint development of cascade hydro-power stations in large river basins. The typical annual runoff data are selected to calculate the difference between the calculated results under different representative years. The results show that the cascade operation of cascaded hydro-power stations can significantly increase the overall power generation of cascade and ease the flood risk caused by concentration of flood season.
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Zhong, Chongxin, Yanmeng Xing, Ying Fan e An Zeng. "Predicting the cascading dynamics in complex networks via the bimodal failure size distribution". Chaos: An Interdisciplinary Journal of Nonlinear Science 33, n. 2 (febbraio 2023): 023137. http://dx.doi.org/10.1063/5.0119902.
Testo completoAbstract (sommario):
Cascading failure as a systematic risk occurs in a wide range of real-world networks. Cascade size distribution is a basic and crucial characteristic of systemic cascade behaviors. Recent research works have revealed that the distribution of cascade sizes is a bimodal form indicating the existence of either very small cascades or large ones. In this paper, we aim to understand the properties and formation characteristics of such bimodal distribution in complex networks and further predict the final cascade size. We first find that the bimodal distribution is ubiquitous under certain conditions in both synthetic and real networks. Moreover, the large cascades distributed in the right peak of bimodal distribution are resulted from either the failure of nodes with high load at the first step of the cascade or multiple rounds of cascades triggered by the initial failure. Accordingly, we propose a hybrid load metric (HLM), which combines the load of the initial broken node and the load of failed nodes triggered by the initial failure, to predict the final size of cascading failures. We validate the effectiveness of HLM by computing the accuracy of identifying the cascades belonging to the right and left peaks of the bimodal distribution. The results show that HLM is a better predictor than commonly used network centrality metrics in both synthetic and real-world networks. Finally, the influence of network structure on the optimal HLM is discussed.
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Khokhlov, S. S., A. G. Bogdanov, V. A. Khomyakov, V. V. Kindin, R. P. Kokoulin, A. A. Petrukhin, V. V. Shutenko e I. I. Yashin. "Energy spectrum of cascade showers initiated by cosmic ray muons in the Cherenkov water detector". EPJ Web of Conferences 208 (2019): 08018. http://dx.doi.org/10.1051/epjconf/201920808018.
Testo completoAbstract (sommario):
Results of analysis of experimental data on cascade showers with energies of 0.1 – 10 TeV initiated by muons in the Cherenkov water detector NEVOD are presented. The method of selection and reconstruction of cascade parameters in the volume of the detector is discussed. Experimental distributions of cascade axes in zenith angle and energy spectrum of cascades are obtained. The measured distributions are compared with results of calculations.
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Liu, Bo, Qidong Chen, Jun Li e Xiaochen Mao. "Novel Optimization Design Methods of Highly Loaded Compressor Cascades Considering Endwall Effect". Entropy 24, n. 6 (15 giugno 2022): 830. http://dx.doi.org/10.3390/e24060830.
Testo completoAbstract (sommario):
The endwall effect has a great impact on the aerodynamic performance of compressor blades. Based on three conventional near-endwall blade modeling methods of bowed blade, endbend blade and leading-edge strake blade (LESB), two combined optimization design methods of highly loaded blades have been developed considering the endwall effect in the current study, i.e., the bowed blade combined with the LESB (bowed LESB blade) and the endbend blade combined with the LESB (endbend LESB blade). Optimization designs were conducted for a compressor cascade with low solidity by using the two combined modeling methods and the three conventional modeling methods, and the optimization results were compared and analyzed in detail. The results showed that the five optimization modelling methods could all improve the performance for the original cascade, and the optimized cascade with the bowed LESB modeling method has the best aerodynamic performance. The total pressure loss of the optimal bowed LESB cascade was only 40.3% of that in the original cascade while reducing the solidity of the original cascade from 1.53 to 1.25 and keeping the static pressure rise and diffusion factor at the same level as the original one. Among the optimal cascades, the radial migration height of the low-energy fluid and the corresponding vortex have great effects on the aerodynamic performance, and the optimal bowed LESB cascade is superior to the other optimal cascades in this aspect.
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Uryson, Anna. "Influence of Extragalactic Magnetic Fields on Extragalactic Cascade Gamma-Ray Emission". Universe 8, n. 11 (29 ottobre 2022): 569. http://dx.doi.org/10.3390/universe8110569.
Testo completoAbstract (sommario):
We discuss the influence of extragalactic magnetic fields on the intensity of gamma-ray emission produced in electromagnetic cascades from ultra-high energy cosmic rays propagating in extragalactic space. Both cosmic rays and cascade particles propagate mostly out of galaxies, galactic clusters, and large-scale structures, as their relative volume is small. Therefore, their magnetic fields weakly affect emission produced in cascades. Yet, estimates of this influence can be useful in searching for dark matter particles when components of extragalactic gamma-ray background should be known, including cascade gamma-ray emission. To study magnetic field influence on cascade emission, we calculated cosmic particle propagation in fields of ~10−6 and 10−12 G (the former is typical inside galaxies and clusters and the latter is common in voids and outside galaxies and clusters). The calculated spectra of cascade gamma-ray emissions are similar in the range of ~107–109 eV, so analyzing cascade emission in this range it is not necessary to specify models of an extragalactic magnetic field.
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Aizyatullova, G. R., L. V. Pashkova e T. K. Sakharnova. "Characteristic of cascades in sports aerobics". Physical Culture Sport Tourism Motor Recreation 8, n. 4 (31 ottobre 2023): 13–17. http://dx.doi.org/10.47475/2500-0365-2023-8-4-13-17.
Testo completoAbstract (sommario):
This article is devoted to the topical issue concerning the substantiation of the content and characteristics of cascade elements in sports aerobics. Each competitive composition of the strongest athletes of Russia and the world contains the sequential performance of two or three elements of complexity and acrobatics, the content of which depends on the degree of physical and technical fitness of the gymnast. Moreover, the demonstration of cascade exercises in a competitive composition gives an advantage to the athlete in the form of additional points, the so-called allowance, for one or another type of cascade. Relevance. In various sports, mainly gymnastics, the concept of cascade has been used for a long time. The appearance of cascades in sports aerobics introduced additional difficulty into the competitive composition of athletes and, as a result, bonuses and an increase in overall performance in competitions. However, the cascades themselves are complex, diverse, allowing you to combine elements of difficulty and elements of acrobatics, components of competitive activity, without which it is impossible for high-class athletes to perform at international level competitions. It is worth recalling that the connection of two and/or three elements in a different sequence, in accordance with the Competition Rules (2016–2020) [4], is allowed, which cannot be said about acrobatic elements. The connection of two acrobatic elements, following one after another in turn, is prohibited, but at the same time, in combination with elements of difficulty, it is allowed. Problem, goal, tasks. To determine the most common cascades in the competitive composition of highly qualified athletes at the championships of Russia and the world in order to further predict the trend in the development of cascade exercises. Research materials and methods. The analysis of scientific and methodological literature was carried out; analysis of documents regulating the activities of a sport, video analysis of the competitive composition of the Russian Championship 2020 and 2021, World Championships (2016 and 2018) and Europe (2019). Results and discussion. As a result of the research, the most common cascades in sports aerobics were determined: cascade from elements of complexity, cascade from elements of complexity and elements of acrobatics, the classification of cascades was given. Conclusion. The most common cascade in sports aerobics is a combination of two and/or three elements of complexity, basically, these are elements from the structural groups “Jumps” and “Dynamic strength”.
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Beguerisse-Díaz, Mariano, Radhika Desikan e Mauricio Barahona. "Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction". Journal of The Royal Society Interface 13, n. 121 (agosto 2016): 20160409. http://dx.doi.org/10.1098/rsif.2016.0409.
Testo completoAbstract (sommario):
Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction.
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Zhu, Ya-Hong, e Jian Jiao. "Automatic Control of Mobile Industrial Robot Based on Multiobjective Optimization Strategy". Journal of Electrical and Computer Engineering 2022 (27 marzo 2022): 1–7. http://dx.doi.org/10.1155/2022/7825906.
Testo completoAbstract (sommario):
In order to solve the optimal cascade mobile path selection problem when mobile industrial robots repair network coverage holes, a cascade mobile path selection optimization method considering the number and energy of intermediate cascade nodes is proposed. By calculating the energy availability of intermediate cascade nodes, this method further obtains the energy availability and decisive energy of each path, selects the optimal cascade mobile path from the perspective of multiobjective optimization, effectively balances the energy consumption of each mobile industrial robot, makes full use of the energy of the whole network, and prolongs the survival time of the network. Simulation results show that the optimization method has higher network energy efficiency than the standard cascaded mobile method.
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Louthan, Allison, Emily Valencia, Dino J. Martins, Travis Guy, Jacob Goheen, Todd Palmer e Daniel Doak. "Large mammals generate both top-down effects and extended trophic cascades on floral-visitor assemblages". Journal of Tropical Ecology 35, n. 4 (11 giugno 2019): 185–98. http://dx.doi.org/10.1017/s0266467419000142.
Testo completoAbstract (sommario):
AbstractCascading effects of high trophic levels onto lower trophic levels have been documented in many ecosystems. Some studies also show evidence of extended trophic cascades, in which guilds dependent on lower trophic levels, but uninvolved in the trophic cascade themselves, are affected by the trophic cascade due to their dependence on lower trophic levels. Top-down effects of large mammals on plants could lead to a variety of extended trophic cascades on the many guilds dependent on plants, such as pollinators. In this study, floral-visitor and floral abundances and assemblages were quantified within a series of 1-ha manipulations of large-mammalian herbivore density in an African savanna. Top-down effects of large mammals on the composition of flowers available for floral visitors are first shown, using regressions of herbivore activity on metrics of floral and floral-visitor assemblages. An extended trophic cascade is also shown: the floral assemblage further altered the assemblage of floral visitors, according to a variety of approaches, including a structural equation modelling approach (model with an extended trophic cascade was supported over a model without, AICc weight = 0.984). Our study provides support for extended trophic cascades affecting floral visitors, suggesting that trophic cascades can have impacts throughout entire communities.
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Cao, Puyu, Luanjiao Liu, Jinfeng Zhang, Guidong Li, Rui Zhu e Zhiqin Yang. "A Study of the Hydrodynamic Characteristics of Two-Dimensional Tandem Cascades". Water 16, n. 5 (26 febbraio 2024): 679. http://dx.doi.org/10.3390/w16050679.
Testo completoAbstract (sommario):
In comparison to single-row cascades, tandem cascades offer the advantages of reduced losses and enhanced operational capabilities, making them widely employed in compressor applications. However, current research on tandem cascades in hydraulic equipment remains relatively limited. In order to explore the potential application of two-dimensional tandem cascade structures in hydrodynamics and investigate their performance differences from single-row cascades, this study proposes a design scheme for a tandem cascade based on an existing single-row cascade design. Numerical simulation technology is utilized to compare and analyze the impact of these two designs on various flow losses under identical working conditions. The results indicate that compared to single-row vanes, the vane configuration of a serial-row design can better reduce losses and increase the pressure difference between the upper and lower surfaces of the vanes, thereby enhancing their load-bearing capacity and stability. This research finding is expected to provide valuable insights for future water pump design and optimization.
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Liu, Baojie, Hengtao Shi e Xianjun Yu. "A new method for rapid shock loss evaluation and reduction for the optimization design of a supersonic compressor cascade". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, n. 13 (23 giugno 2017): 2458–76. http://dx.doi.org/10.1177/0954410017715277.
Testo completoAbstract (sommario):
A one-dimensional analytical shock loss prediction method was proposed to tailor the shock system, i.e. the strength of the first and second passage shock, and reduce the shock loss in a supersonic cascade. To develop the one-dimensional analytical model, the shock system in a supersonic cascade was divided into four processes which can be seen in most supersonic compressor cascade, i.e. the flow upstream the extending-external shock, the flow between the extending-external shock and the first passage shock, the accelerating flow from the first passage shock to the second passage shock, and the flow downstream of the second passage shock. Based on some flow assumptions and experimental empirical correlations, the complex flows, containing the shock system, in the blade passage of a supersonic compressor cascade could be described with one-dimensional relationships, which can be used to predict shock losses along the flow passage rapidly and determine the shock system improving direction for achieving lower shock loss while keeping the same cascade static pressure ratio. In order to validate the one-dimensional analytical method, the shock system of two supersonic cascades ARL-SL19 and DLR-PAV-1.5 are modified based on the analysis of the model. The modified cascades achieved about 29% and 25% reduction of shock loss at redesign point compared with baseline cascades, respectively.
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Cho, C.-H., S.-Y. Cho, S. E. Gorrell, K.-Y. Ahn e Y.-C. Kim. "An inverse design of a double-pitch passage for an infinite cascade model experiment". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 224, n. 1 (11 agosto 2009): 157–67. http://dx.doi.org/10.1243/09544062jmes1552.
Testo completoAbstract (sommario):
In this study, sidewalls of a turbine cascade experimental apparatus are designed to satisfy periodic flow conditions with two blades without any flow control or tailboards. Generally, the turbine cascade experimental apparatus needs removing fluid from the cascade walls or adjusting tailboards located downstream of the cascade to establish periodic flow conditions through the cascade blades. If a linear turbine cascade often consists of only a few blades within a passage, advantages to this experimental arrangement are increased from using larger turbine cascades, a lower mass flowrate and corresponding decrease in required power, and easier optical access within the cascade passage. However, fewer blades in the cascade make it difficult to establish periodic flow conditions between blades compared to infinite cascade flow conditions. In order to test a turbine cascade with a few blades without flow control devices, only two turbine blades are installed within a double-pitch passage. Sidewall shape is designed with 12 geometric design variables using a gradient-based optimization method, and surface isentropic Mach number distribution on the blades is chosen for the existence of periodic flow conditions. The computed result shows periodic flow conditions obtained by modifying only the sidewalls of the double-pitch passage as a cascade experimental apparatus.
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Rehberger, Max, e Michael Hiete. "Allocation Procedures for Generic Cascade Use Cases - An Evaluation Using Monte Carlo Analysis". Materials Science Forum 959 (giugno 2019): 32–45. http://dx.doi.org/10.4028/www.scientific.net/msf.959.32.
Testo completoAbstract (sommario):
Cascade use - a concept for increasing resource efficiency by multiple use of resources - gains in importance, in particular for bio-based materials. Allocation of environmental burdens and costs along the cascade chain plays a major role in deciding whether to establish a cascade or not. This highlights the need for a methodology for properly assessing different types of cascades. To provide guidance in terms of choice of allocation procedure available from life cycle assessment (LCA), Monte Carlo analysis is used. Especially hybrid, individually tailored allocation approaches can be evaluated in this way. The results show a high diversity of possible outcomes in terms of general allocation intensity (how much burden is shifted between steps of the cascade), rank reversals (exchange of positions inside the burden ranking) and variance of the overall results of the cascade allocation. Results are valuable for selecting an allocation procedure for cascade LCA and for further interpreting cascade models using specific allocation procedures.
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Bakir, F., S. Kouidri, T. Belamri e R. Rey. "On a General Method of Unsteady Potential Calculation Applied to the Compression Stages of a Turbomachine—Part I: Theoretical Approach". Journal of Fluids Engineering 123, n. 4 (6 giugno 2001): 780–86. http://dx.doi.org/10.1115/1.1399286.
Testo completoAbstract (sommario):
An algorithm using the singularity method was developed. It allows taking into account the interaction between fixed and mobile cascades. Its principle is based on the summation of discrete vortices distributed periodically on the rotor and stator profiles. The overall matrix, obtained by applying the boundary conditions, takes into account the complexity of the studied cascade geometry (presence or not of splitter blades, possibly variable pitch of the profiles, etc…) To illustrate the interest and the impact of the algorithm, two parametric studies on turbomachines cascade are presented: Planes cascade made up of a rotor and a stator (at the mean radius of an axial fan). Circular cascade made up of impeller and a volute (peripheral cascade of a centrifugal pump).
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Poletaev, Gennady, Darya Novoselova, Mikhail D. Starostenkov, Vladimir Tsellermaer e Viktor Kovalenko. "The Study of Inhibition of Atom-Atom Collisions Cascades by Ni-Al (100) Interphase Boundary". Key Engineering Materials 685 (febbraio 2016): 8–12. http://dx.doi.org/10.4028/www.scientific.net/kem.685.8.
Testo completoAbstract (sommario):
The interaction of atom-atom collisions cascades with Ni-Al interphase boundary was studied by the method of molecular dynamics. It was shown that the interphase boundary partially absorbs the cascade energy. The degree of energy absorption of the cascade by the interphase boundary increases with the growth of the structural imperfection of the boundary and density of the misfit dislocations, and also with increase of distance between the boundary and the place of the cascade initiation.
40
Min, Byungjoon, e Maxi San Miguel. "Threshold Cascade Dynamics in Coevolving Networks". Entropy 25, n. 6 (13 giugno 2023): 929. http://dx.doi.org/10.3390/e25060929.
Testo completoAbstract (sommario):
We study the coevolutionary dynamics of network topology and social complex contagion using a threshold cascade model. Our coevolving threshold model incorporates two mechanisms: the threshold mechanism for the spreading of a minority state such as a new opinion, idea, or innovation and the network plasticity, implemented as the rewiring of links to cut the connections between nodes in different states. Using numerical simulations and a mean-field theoretical analysis, we demonstrate that the coevolutionary dynamics can significantly affect the cascade dynamics. The domain of parameters, i.e., the threshold and mean degree, for which global cascades occur shrinks with an increasing network plasticity, indicating that the rewiring process suppresses the onset of global cascades. We also found that during evolution, non-adopting nodes form denser connections, resulting in a wider degree distribution and a non-monotonous dependence of cascades sizes on plasticity.
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Zheng, Huan, e Zhenggui Zhou. "Corner separation control in compressor stators with jets from the blade leading edge". Advances in Mechanical Engineering 15, n. 2 (febbraio 2023): 168781322311524. http://dx.doi.org/10.1177/16878132231152408.
Testo completoAbstract (sommario):
Corner separation occurs easily in highly loaded compressor stators. This paper proposes a novel slot inside the stator blade, with the slot inlet located at the blade leading edge and the slot outlet located at the suction surface, by using the momentum of the incoming flow to form a high velocity jet to control the development of the boundary layer on the blade suction surface. For 3D compressor cascades, the influence of the key geometrical slot parameters on the flow fields in the slot and cascade passage and the aerodynamic performance of the cascade were investigated with a numerical method. Then, the stator blades in a highly loaded compressor stage were slotted to improve the flow in the stator blade passages. The main results can be summarized as follows. The use of slotted blades in the cascade effectively suppresses corner separation. When the cascade inlet velocity is high or the inlet flow is at a positive attack angle, the separation control effect improves. In the highly loaded compressor stage, slotted stator blades considerably reduced the flow loss at the stator corner, and the stage efficiency increased over the entire flow rate range. Furthermore, two cascades with unslotted and slotted blades were tested. The experimental and numerical results were consistent, demonstrating that the total pressure loss coefficient of a cascade can be effectively reduced by slotting the blades in the cascade.
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Bartnik, Adam, Piotr Moniewski e Przemysław Tomalski. "Seasonality Of The Basic Physical And Chemical Characteristics Of Water Flowing Through The Cascades Of Small Reservoirs In Urban And Suburban Areas". Limnological Review 13, n. 2 (1 giugno 2013): 63–71. http://dx.doi.org/10.2478/limre-2013-0007.
Testo completoAbstract (sommario):
Abstract The paper showed the changes of characteristics of river water flowing through the cascades of reservoirs. One of the cascades is located in a highly urbanized area of Lodz. The second is in a suburban area on the northern outskirts of Lodz agglomeration. However, it still remains under the influence of storm water discharged from the highway. Every 2 weeks, in 4 monitoring points (on the input and on the output of each cascade), the measurements of basic physical and chemical water parameters were made (using data registered in cross-sections obtained between 2006 and 2012). The analysed characteristics can be divided into three groups: 1. No changes in the seasonal fluctuations of analysed characteristics before and after the cascade of reservoirs and no differences between urban and suburban areas in the influence of the cascades on river water; 2. Significant changes in the seasonal fluctuations of analysed characteristics before and after the cascade of reservoirs and no differences between urban and suburban areas in the influence of the cascades on river water; 3. Significant changes in the seasonal fluctuations of analysed characteristics before and after the cascade of reservoirs and also significant differences between urban and suburban areas in the influence of the cascades on river water. The first group includes the temperature and pH of the water, the second group water conductivity and the third group water turbidity and dissolved oxygen in water.
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Han, Jinyoung, Daejin Choi, Jungseock Joo e Chen-Nee Chuah. "Predicting Popular and Viral Image Cascades in Pinterest". Proceedings of the International AAAI Conference on Web and Social Media 11, n. 1 (3 maggio 2017): 82–91. http://dx.doi.org/10.1609/icwsm.v11i1.14879.
Testo completoAbstract (sommario):
The word-of-mouth diffusion has been regarded as an important mechanism to advertise a new idea, image, technology, or product in online social networks (OSNs). This paper studies the prediction of popular and viral image diffusion in Pinterest. We first characterize an image cascade from two perspectives: (i) volume — how large the cascade is, that is, total number of users reached, and (ii) structural virality — how many users in the cascade are responsible for attracting other users. Our model predicts whether an image will be (a) popular in terms of the volume of its cascade, or (b) viral in terms of the structural virality. Our analysis reveals that a popular image is not necessarily viral, and vice versa. This motivates us to investigate whether there are distinctive features for accurately predicting popular or viral image cascades. To predict the popular or viral image cascades, we consider the following feature sets: (i) deep image features, (ii) image meta and poster's information, and (iii) initial propagation pattern. We find that using deep image features alone is not as effective in predicting popular or viral image cascades. We show that image meta and poster's information are strong predictors for predicting popular image cascades while image meta and initial propagation patterns are useful to predict viral image cascades. We believe our exploration can give an important insight for content providers, OSN operators, and marketers in predicting popular or viral image diffusion.
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Takahashi, Akiyuki, Kotoko Hirose, Naoki Soneda e Masanori Kikuchi. "Molecular Dynamics Simulation of Displacement Cascade in α-Zr". Key Engineering Materials 306-308 (marzo 2006): 923–28. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.923.
Testo completoAbstract (sommario):
In this work, the point defect production in α-Zr at 600K by displacement cascade with Primary Knock-on Atom (PKA) energy up to 20KeV has been investigated by molecular dynamics (MD) simulations. Especially, the influence of subcascades formation on the point defect and cluster production in 20keV cascades has been investigated in detail. The subcascade formation was seen in 36 cases of 20keV cascade simulations out of 50 cases. As the damaged areas are divided into many small areas, the maximum size of point defect cluster tends to decrease when the displacement cascade is settled. On the other hand, subcascades formation has not had an influence on the number of Frenkel pairs in final state of the 20keV cascades comparatively.
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Babichev A.V., Kolodeznyi E.S., Gladyshev A.G., Denisov D.V., Jollivet A., Quach P., Karachinsky L. Ya. et al. "Heterostructure of a 2.5 THz range quantum-cascade detector". Semiconductors 56, n. 3 (2022): 259. http://dx.doi.org/10.21883/sc.2022.03.53069.9750.
Testo completoAbstract (sommario):
The design of the heterostructure of a 2.5 THz range quantum-cascade detector is proposed and heterostructure is grown by molecular-beam epitaxy technique. To optimize the thicknesses of the layers of the heterostructure cascades, a numerical method for iterative solution of the Schrodinger--Poisson equation in the k· p formalism was used. The grown heterostructure of the quantum-cascade detector showed a high structural perfection, confirmed by the small values of the average FWHM of the high-order satellite peaks on the X-ray diffraction rocking curves, which were (8.3±0.5)n. Analysis of dark-field images obtained by transmission electron microscopy showed that the total thickness of the layers in the cascade is (137.3±6.9) nm, which corresponds to the calculated thickness of the layers in the cascade of the heterostructure of the quantum-cascade detector. Keywords: superlattices, quantum-cascade detector, epitaxy, gallium arsenide
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BABIANO, ARMANDO, e ANTONELLO PROVENZALE. "Coherent vortices and tracer cascades in two-dimensional turbulence". Journal of Fluid Mechanics 574 (15 febbraio 2007): 429–48. http://dx.doi.org/10.1017/s0022112006004265.
Testo completoAbstract (sommario):
We study numerically the scale-to-scale transfers of enstrophy and passive-tracer variance in two-dimensional turbulence, and show that these transfers display significant differences in the inertial range of the enstrophy cascade. While passive-tracer variance always cascades towards small scales, enstrophy is characterized by the simultaneous presence of a direct cascade in hyperbolic regions and of an inverse cascade in elliptic regions. The inverse enstrophy cascade is particularly intense in clusters of small-scales elliptic patches and vorticity filaments in the turbulent background, and it is associated with gradient-decreasing processes. The inversion of the enstrophy cascade, already noticed by Ohkitani (Phys. Fluids A, vol. 3, 1991, p. 1598), appears to be the main difference between vorticity and passive-tracer dynamics in incompressible two-dimensional turbulence.
47
Trulev, A. V., V. O. Lomakin, I. V. Klindukh, V. S. Udovitskiy e S. F. Timushev. "Design Features of Impeller Vane Cascades to Pump Gas and Liquid Mixtures Conducive to Reducing Gas Cavern Magnitudes". Proceedings of Higher Educational Institutions. Маchine Building, n. 9 (750) (settembre 2022): 73–82. http://dx.doi.org/10.18698/0536-1044-2022-9-73-82.
Testo completoAbstract (sommario):
We employed numerical simulation methods to investigate how design features of impeller vane cascades in a centrifugal pump processing gas and liquid mixtures will affect the magnitude of gas caverns. We derived a mathematical model for multiphase flow of incompressible fluid. We performed hydrodynamic computations for various impeller vane cascade designs. We identified regions of local gas separation in commercially available and improved cascades that may result in gas plug formation and pump failure. The paper investigates the effect of the following parameters on the magnitude of a gas cavern: the angle of attack, pressure feed, pressure gradient, and the presence of through holes and transverse cutouts in a single-tier vane cascade. We consider design features of stacked van cascades and investigate how the vane length and vane distribution uniformity in the blading section of a stacked vane system affect gas cavern magnitudes. We selected the optimum vane cascade design for multiphase impellers. The paper then indicates further lines of research.
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Zhou, Bangzhu, Xiaodong Feng e Hemin Feng. "Structural-topic aware deep neural networks for information cascade prediction". PeerJ Computer Science 10 (19 febbraio 2024): e1870. http://dx.doi.org/10.7717/peerj-cs.1870.
Testo completoAbstract (sommario):
It is critical to accurately predict the future popularity of information cascades for many related applications, such as online opinion warning or academic influence evaluation. Despite many efforts devoted to developing effective prediction approaches, especially the recent presence of deep learning-based model, the structural information of the cascade network is ignored. Thus, to make use of the structural information in cascade prediction task, we propose a structural-topic aware deep neural networks (STDNN), which firstly learns the structure topic distribution of each node in the cascade, feeds it to a sequential neural network, and finally predicts the future popularity of the cascades. It can inherit the high interpretability of Hawkes process and possesses the high predictive power of deep learning methods, bridging the gap between prediction and understanding of information cascades by capturing indicative graph structures. We evaluate our model through quantitative experiments, where our model exhibits promising performance, efficiency higher than the baselines.
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Fateev, Ilja V., Maria A. Kostromina, Yuliya A. Abramchik, Barbara Z. Eletskaya, Olga O. Mikheeva, Dmitry D. Lukoshin, Evgeniy A. Zayats et al. "Multi-Enzymatic Cascades in the Synthesis of Modified Nucleosides: Comparison of the Thermophilic and Mesophilic Pathways". Biomolecules 11, n. 4 (16 aprile 2021): 586. http://dx.doi.org/10.3390/biom11040586.
Testo completoAbstract (sommario):
A comparative study of the possibilities of using ribokinase → phosphopentomutase → nucleoside phosphorylase cascades in the synthesis of modified nucleosides was carried out. Recombinant phosphopentomutase from Thermus thermophilus HB27 was obtained for the first time: a strain producing a soluble form of the enzyme was created, and a method for its isolation and chromatographic purification was developed. It was shown that cascade syntheses of modified nucleosides can be carried out both by the mesophilic and thermophilic routes from D-pentoses: ribose, 2-deoxyribose, arabinose, xylose, and 2-deoxy-2-fluoroarabinose. The efficiency of 2-chloradenine nucleoside synthesis decreases in the following order: Rib (92), dRib (74), Ara (66), F-Ara (8), and Xyl (2%) in 30 min for mesophilic enzymes. For thermophilic enzymes: Rib (76), dRib (62), Ara (32), F-Ara (<1), and Xyl (2%) in 30 min. Upon incubation of the reaction mixtures for a day, the amounts of 2-chloroadenine riboside (thermophilic cascade), 2-deoxyribosides (both cascades), and arabinoside (mesophilic cascade) decreased roughly by half. The conversion of the base to 2-fluoroarabinosides and xylosides continued to increase in both cases and reached 20-40%. Four nucleosides were quantitatively produced by a cascade of enzymes from D-ribose and D-arabinose. The ribosides of 8-azaguanine (thermophilic cascade) and allopurinol (mesophilic cascade) were synthesized. For the first time, D-arabinosides of 2-chloro-6-methoxypurine and 2-fluoro-6-methoxypurine were synthesized using the mesophilic cascade. Despite the relatively small difference in temperatures when performing the cascade reactions (50 and 80 °C), the rate of product formation in the reactions with Escherichia coli enzymes was significantly higher. E. coli enzymes also provided a higher content of the target products in the reaction mixture. Therefore, they are more appropriate for use in the polyenzymatic synthesis of modified nucleosides.
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Rohr, Julia K., Jennifer Manne-Goehler, Francesc Xavier Gómez-Olivé, Ryan G. Wagner, Molly Rosenberg, Pascal Geldsetzer, Chodziwadziwa Kabudula et al. "HIV treatment cascade for older adults in rural South Africa". Sexually Transmitted Infections 96, n. 4 (26 giugno 2019): 271–76. http://dx.doi.org/10.1136/sextrans-2018-053925.
Testo completoAbstract (sommario):
ObjectivesThe HIV treatment cascade is a powerful framework for understanding progress from initial diagnosis to successful treatment. Data sources for cascades vary and often are based on clinical cohorts, population cohorts linked to clinics, or self-reported information. We use both biomarkers and self-reported data from a large population-based cohort of older South Africans to establish the first HIV cascade for this growing segment of the HIV-positive population and compare results using the different data sources.MethodsData came from the Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa (HAALSI) 2015 baseline survey of 5059 adults aged 40+ years. Dried blood spots (DBS) were screened for HIV, antiretroviral drugs and viral load. In-home surveys asked about HIV testing, diagnosis and antiretroviral therapy (ART) use. We calculated proportions and CIs for each stage of the cascade, conditional on attainment of the previous stage, using (1) biomarkers, (2) self-report and (3) both biomarkers and self-report, and compared with UNAIDS 90-90-90 targets.Results4560 participants had DBS results, among whom 1048 (23%) screened HIV-positive and comprised the denominator for each cascade. The biomarker cascade showed 63% (95% CI 60 to 66) on ART and 72% (95% CI 69 to 76) of those on ART with viral suppression. Self-reports underestimated testing, diagnosis and ART, with only 47% (95% CI 44 to 50) of HIV-positive individuals reporting ART use. The combined cascade indicated high HIV testing (89% (95% CI 87 to 91)), but lower knowledge of HIV-positive status (71% (95% CI 68 to 74)).ConclusionsOlder South Africans need repeated HIV testing and sustained ART to reach 90-90-90 targets. HIV cascades relying on self-reports are likely to underestimate true cascade attainment, and biomarkers provide substantial improvements to cascade estimates.